Nervous System Study Guide PDF

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NERVOUS SYSTEM STUDY GUIDE FOR MIDTERM 4/23/18 PART 1 – NERVOUS SYSTEM GENERAL ➢ Describe the functions of the nervous system – how information flows in this system The nervous system is hardwired. It is in charge of things that have to happen rapidly. The three basic functions of the nervous system as a whole are communication, control, coordination. ➢ Know the anatomical & functional organization of the nervous system Cells = neurons + neuroglia (glia = glue) → Nervous Tissue = Grey matter + white matter in Central Nervous system → Organs = Brain + spinal cord in Central Nervous System also nerves + ganglia in Peripheral Nervous System → Systems = Central Nervous System & Peripheral Nervous System Nervous System Hierarchy ↓ Central Nervous System + Peripheral nervous system ↓ Sensory Division + Motor Division ↓ ↓ General + Special Somatic + Autonomic -Touch -Smell -Pain -Taste -Temp -Vision -Stretch -Hearing -Pressure -Equilibrium -Proprioception ➢ Differentiate all pairs of vocabulary words as given on handout Nervous System = Uses electrical impulses through neurons Endocrine System = Uses hormones Central Nervous System = It is so important, it is covered by bone and performs integration Peripheral Nervous System = Carries out commands Sensory = Gathers information and carries signals from outside towards the central nervous system Motor = Carries signals from central nervous system out to the body Afferent = Sensory neurons that carry nerve impulses from stimuli towards the CNS + brain Efferent = Motor neurons that carry impulses away from CNS → muscle for movement Somatic = Voluntary: effector is skeletal muscle tissue Autonomic = Involuntary: effector is smooth muscle tissue, cardiac muscle tissue, and glands Sympathetic = Responds to emergencies Parasympathetic = Maintains homeostasis General Senses = Body wide – touch, pain, temperature, stretch, pressure, proprioception Special Senses = Smell, taste, vision, hearing, equilibrium Grey matter = Made of unmyelinated axons organized into nuclei (clusters of cell bodies) located in the cortex or grey horns of the Central Nervous System White matter = Myelinated axons organized into tracts (bundles of axons)

Horn = Have cell bodies of some kind of motor neuron Column = Nuclei = Grey matter in the CNS Cortex = Outer layer (Grey matter) in the brain Nuclei = Grey matter in CNS Tracts = Bundles of myelinated axons in white matter in the CNS Nuclei = Grey matter in the CNS Ganglia = A structure containing a number of nerve cell bodies, typically linked by synapses Tract = Bundles of myelinated axons in white matter in the CNS Nerve = Bundle of axons Nerve = Bundle of axons Ganglion = Collection of cell bodies Nerve = Bundle of axons Neuron = A specialized cell transmitting nerve impulses; a nerve cell. Neuron = A specialized cell transmitting nerve impulses; a nerve cell. Neuroglia = Glue which function to support neurons Cranial Nerves = Either sensory or motor or mixed neurons Spinal Nerves = All have both sensory and motor neurons Axon = Take information away from the cell body and splits to become the neuromuscular junction Dendrite (Nerve Fibers) = Take information towards cell body Reflex = Sensory division of the PNS (the receptors) take info which is carried by sensory neurons in a nerve to the CNS and integration is performed by the interneurons and then info is carried by motor neurons in a nerve to the effectors which are the motor division of the PNS. Reflex Arc = The entire process from RECEPTOR to EFFECTOR depending on whether or not the reflex will be positive or negative Withdrawal Reflex Arc = pathway of information for performing a reflex Autonomic Reflex Arc = Neurons talk to neurons talk to neurons until they talk to an effector Synapse = Point of communication between synaptic knob and some other cell (could be another neuron or effector) General Sensory neurons are always unipolar ➢ Describe the components of gray matter vs. white matter Gray matter is located in the central nervous system. Specifically, it is located in the cerebral cortex of the brain and the posterior, lateral, and anterior grey horns of the spinal cord. Gray matter is made of primarily of unmyelinated axons, cell bodies, and dendrites. White matter is located in the central nervous system. Specifically, it is located in the corona radiata of the brain and in the posterior, lateral, and anterior funiculi of the spinal cord. White matter is also organized into tracts (bundles of axons) and is bundles of myelinated axons

➢ Note features that serve to increase surface area in the brain The most notable and famous features are the sulci and gyri of the brain in the cortex which increase much surface area. Folia is also folds of cerebellar cortex which is located on the cerebellum. There are also spaces inside the brain. ➢ Note that the complexity of the nervous system lies in its wiring (practice drawing basic diagrams) Two types of wiring in the autonomic nervous system. Parasympathetic wiring has to do with heart rate and beat force decrease and stimulates smooth muscle + glands in digestive tract + urinary bladder + erection Sympathetic wiring is more complex as it controls heart rate and beat force increase. It also is involved in pupil dilation to let more light in and works to engage arrector pili muscle and eccrine glands. It controls smooth Muscle Tissue in Blood vessel walls. It is involved in ejaculation. ➢ Name the components of a reflex arc; differentiate reflex arc from a reflex Not entirely sure what she is referring to by the wording of this question PART II – CELLS ➢ Contrast the histological characteristics, function and location of neurons and neuroglia Neurons are amitotic (meaning they do not divide). They come from stem cells and can only regenerate if it is in the peripheral nervous system. They use a TON of energy and need a lot of oxygen and glucose. The neuron is composed of a cell body, dendrites which take information towards the cell body, the axons (which can travel and split along the way). The synapse isn’t exactly the neuron but it is the point of communication between the synaptic knob and some other cell (could be another neuron or an effector which is a muscle or a gland) Neuroglia is the glue that holds everything together. It is made up of 6 specific cell types; 4 of the cells are in the CNS and 2 are in the PNS. Some can attach themselves to neurons while other have completely separate functional purposes. Astrocytes are the most abundant types of glial cells in the CNS as they have many perivascular feet and give structural support to neurons and capillaries. They are important to form the blood brain barrier which allows astrocytes to control what leaks out of the capillaries into nervous tissue. There are also ependymal cells in the CNS which line ventricles of the brain and central canal of the spinal cord, microglial cells which are resident macrophages of CNS (general phagocytosis), and oligodendrocytes which have processes that wrap around some axons to form a myelin sheath. The two cells in the peripheral nervous system are Schwann cells which myelinate some axons in the PNS and have multiple layers of plasma membrane (neurolemma) and they secrete nerve growth factor.

➢ Classify neurons by structure and function; know location of each part (Cell body, dendrites, axon Cell body is the main part of the neuron. Dendrites come off of the cell body. Axons take the information away from the cell body towards other neurons, muscles, or glands. There are three main types of axons; sensory neuron, interneuron, motor neuron. There are three structures that correspond with the types of axons; unipolar (only one process emerging from the cell), bipolar (have two processes which extend from each end of the cell body, and multipolar (have one axon or two or more dendrites).

➢ Compare the different ways that axons may be found: naked, with neurolemma, myelinated, etc. There are 4 types of possibilities axons can have: 1. Myelinated axons in the CNS (by oligodendrocytes) 2. Myelinated axons in the PNS (by Schwann cells) 3. Unmyelinated axons in the CNS (NAKED) 4. Unmyelinated axons in the CNS (a little protection from Schwann cells but mainly protected by neurolemma)

➢ What structure is essential for regeneration of peripheral nervous tissue Schwann Cells secrete nerve growth factor

PART III – SPINAL CORD AND SPINAL NERVES ➢ Describe the anatomical and cross-sectional structures of the spinal cord and structures that protect it The spinal cord is made up of two types of nervous tissue; grey matter and white matter. The grey matter is made up of unmyelinated axons, a bunch of cell bodies, and dendrites. The white matter is made up of myelinated axons which are organized into bundles of axons called tracts. In the spinal cord the white matter tracts are called the posterior, anterior, and lateral funiculus. Each individual funiculus (white matter) has different types of neurons; posterior has general sensory neurons ONLY, anterior has general sensory and somatic motor neurons, lateral has a ton of general sensory and somatic motor but also autonomic motor tracts. Grey matter in the spinal cord is made up of horns; posterior horns have cell bodies of interneurons, anterior horns have cell bodies of somatic motor neurons, and lateral horns have cell bodies of preganglionic autonomic motor neurons. Aside from the tissue that makes up the spinal cord itself, it also consists of several components exteriorly. Specifically, it consists of meninges which are CT coverings which also cover the brain. The meninges consist of; epidural space, dura mater, subdural space, arachnoid layer, subarachnoid space, pia mater. There are also denticulate ligaments that are extensions of the pia that attach to the dura.

➢ Meningeal Layers in order, associated spaces, what fills each space Starts with the epidural space which is around the spinal cord only, next is the dura mater which is a white fibrous CT layer which is continuous with epineurium, then subdural space, then arachnoid layer, then subarachnoid space which is filled with CSF, finally pia mater which is stuck onto the spinal cord ➢ Describe the composition (hierarchical structure) and CT coverings of a nerve; how are they named Nerve composition – Axon (myelin or not) → Endoneurium (layer of areolar CT) → Fascicles → Perineurium (dense irregular CT) → Nerve (organ) → Epineurium (continuous with dura mater WFCT) ➢ Describe the relationship between vertebrae, spinal nerves, spinal segments, dermatomes and myotomes Spinal nerves are all mixed and there is no such thing as a purely sensory or purely motor spinal nerve! Spinal nerves always exit at the intervertebral foramen. 31 pairs of spinal nerves names for their spinal cord segments; 8 cervical spinal nerves, 12 thoracic spinal nerves, 5 lumbar spinal nerves, 5 sacral spinal nerves, 1 coccygeal spinal nerve Each set of spinal nerves are in between vertebrae. The first spinal nerve emerges between the skull and the atlas. Each spinal nerve innervates one derma tome (skin region sensory) and 1 myotome (motor, muscle group). ➢ Differentiate: dorsal and ventral rootlets, roots, and rami Dorsal ramus is small and is in charge of everything posterior to the intervertebral formina. The ventral ramus is large and it is in charge of everything anterior (it branches). Flow of info – Dorsal root → spinal cord → dorsal ramus, ventral ramus, spinal nerve ➢ Define the term plexus and name the nerve plexuses associated with given named nerves Plexus is a network of nerves. Cervical plexus → phrenic nerve Brachial plexus → radian, median, ulnar nerves Lumbar plexus → Femoral nerve Sacral plexus → tibial, common fibular, and sciatic nerve ➢ List the anatomical structures that contribute to speed of nerve impulse conduction Myelin sheaths (Schwann cells) + nodes of Ranvier

Autonomic Nervous System ➢ Compare and contrast the structural and functional differences between somatic and autonomic nervous systems CONTRAST SOMATIC AUTONOMIC Effector

Skeletal muscle tissue

Action

Voluntary, excitatory [can either give it or not] Conscious = precentral gyrus Subconscious = cerebellum, red nucleus, substantia nigra, caudate, lentiform, corpora quadrigemina, cranial nerve nuclei, pons, medulla oblongata 1

CNS control center

CNS → Effector (number of motor neurons Cell body locations Myelinated axons

Anterior grey horn or CNN Yes

Neurotransmitters

Acetylcholine

Smooth muscle tissue + cardiac muscle tissue + glands Involuntary, excitatory, inhibitory Hypothalamus + cardiovascular control center

2 Lateral grey horn or CNN Preganglionic = yes Postganglionic = no, protected by neurolemma Acetylcholine or Norepinephrine

➢ Compare and contrast the sympathetic and parasympathetic divisions of the autonomic nervous system (both structure and function) CONTRAST SYMPATHETIC PARASYMPATHETIC Function

Location of preganglionic neuron cell body Neuron Length Ganglia location + names

Output

Neurotransmitters

Respond to an emergency (always on excitatory or inhibitory) Thoracolumbar T1 → L2 Lateral Grey horn Preganglionic neurons are short Closer to spinal cord sympathetic trunk ganglia (paired) collateral ganglia Divergent! (ex. 1 preganglionic: 30 postganglionic) Preganglionic → postganglionic = Acetylcholine Postganglionic → effector = norepinephrine

Maintain homeostasis (conserve energy) always on excitatory or inhibitory Craniosacral -CNN (III,VII, IX, X) -Lateral grey horn (S2 → S4) Preganglionic neurons are long In or near the wall of effector terminal ganglia Focused (ex. 1 preganglionic: 4 postganglionic) Preganglionic → postganglionic = Acetylcholine Postganglionic → effector = Acetylcholine

➢ Explain the relationship of the hypothalamus to the Autonomic Nervous System The hypothalamus is apart of the Diencephalon. It is a collection of 12 paired nuclei. It is made up of mammillary bodies which act as the sensory relay station for smell (very anterior). They also link neurons and the endocrine systems so they can both be in charge at the same time of controlling the pituitary gland (master endocrine gland) which secretes hormones that control other endocrine glands. The hypothalamus controls the ENTIRE autonomic nervous system!! It controls the pineal gland and contains homeostatic control centers for temperature, hunger, thirst, and satiety. On top of that, it is the center of the limbic system [emotional brain] which has to do with rage, pleasure, and sex drive. ➢ Explain the relationship of the adrenal medulla to the sympathetic response Cannot find information about this in notes. ➢ Describe how the wiring of the sympathetic division facilitates rapid, mass activation of the effectors Sympathetic wiring is very complex. It has to do with connection for pupil dilation (to let more light in), arrector pili muscle, and eccrine glands, smooth muscle tissue in blood vessel walls, airway dilation, heart rate, beatforce increase, adrenal gland = medulla releases epinephrine (adrenaline = norepinephrine), ejaculation.

➢ Differentiate: sensory and autonomic ganglia, sympathetic and parasympathetic ganglia CONTRAST

SENSORY [DORSAL ROOT] GANGLION

AUTONOMIC GANGLION

Information

General sensory

autonomic motor

Shape of cell body

Unipolar

Multipolar

Synapses

No

Yes [preganglionic → postganglionic]

Linkage between ganglia

No

Some are, sympathetic trunk ganglia/chain ganglia

Brain and cranial nerves ➢ For each of the major parts of the brain know: o 2˙ degree embryonic vesicle, associated ventricle, location, and basic gross anatomy/functions a.) Dorsal hollow nerve cord b.) Anterior end enlarges and forces 1˚ embryonic vesicles to split c.) Further divide to form 2˚ embryonic vesicles → 5 pair

➢ List the central nervous system structures that grows like a rams horn during expansion of the telencephalon Lateral ventricles

➢ List the central nervous system structures involved in control of motor function (conscious or subconscious) The two division under motor division of the nervous system are the somatic and autonomic division. The somatic division is considered voluntary so it’s effector is skeletal muscle tissue. The autonomic division is involuntary and it’s effectors are smooth muscle tissue, cardiac muscle tissue, and glands. ➢ Know the functions in general location of the reticular formation and the limbic system The reticular formation is a network in the brainstem which projects to the spinal cord to help communicate its messages to improve muscle tone and emotional response in the autonomic nervous system (diencephalon) + cerebral cortex. The limbic system functions as the emotional center of the brain and is a network that includes: Hypothalamus and cerebrum. It is related to the autonomic nervous system response. The fibers project from the cerebral cortex to the frontal lobe so that you can weigh consequences. It is also comprised of the hippocampus, fornix, and amygdala.

➢ Identify the cranial nerves by name, number (roman numerals), location, and function CN I: Olfactory Nerve: Odors provoke emotion/ associate w/memories CN II: Optic Nerve: Vision [HYPOTHALAMUS] CN III: Oculomotor Eye movement control [MIDBRAIN] CN IV: Trochlear: Eye movement control [MIDBRAIN] CN V: Trigeminal: Touch, pain, temp, muscles of mastication [PONS] CN VI: Abducens: Eye muscle control [PONS] CN VII: Facial: Facial expression, lacrimal/salivary gland, taste [PONS] CN VIII: Vestibulocochlear: Equilibrium, hearing [PONS] CN IX: Glossopharyngeal: pharynx swallowing, salivation, gen sense, taste, B.P. [MEDULLA] CN X: Vagus: Pharynx & larynx swallowing and speech, control of heart, smooth muscle of airways and gi tract, as well as their glands, visceral sense [MEDULLA] CN XI: Accessory: Swallowing, movement of head and neck [MEDULLA] CN XII: Hypoglossal: Tongue swallowing and speech [MEDULLA]

➢ Describe structure and function of the blood brain barrier; how brain is protected by meninges and cerebrospinal fluid End of the astrocytes contain processes called perivascular feet that wrap around and cover the capillaries in the brain. Blood Brain Barrier controls substances going into nervous tissue from the bloodstream. Protects blood from toxins & nourishes the tissue with nutrients

➢ Explain the formation and circulation of cerebrospinal fluid (through ventricles, subarachnoid space, venous circulation) CSF is produced at the choroid plexus (network of capillaries) then goes to the lateral ventricles → Third ventricle → Fourth ventricle → interventricular foramen → third ventricle → cerebral aqueduct → 4th ventricle → R/L lateral aperture, central canal, or median aperture → subarachnoid space → through arachnoid villi → dural venous sinuses (joins O2 poor blood) → superior sagittal sinus → inferior sagittal sinus → straight sinus → occipital sinus → confluence of sinuses → L/R Transverse sinus → Sigmoid sinus → Jugular foramen → internal jugular veins → R/L brachiocephalic veins → superior vena cava → right atrium Sensory and motor pathways ➢ Explain the clinical importance of knowing the major pathways of the nervous system No explanation of this given ➢ Name some common somatic (cutaneous and proprioceptive) receptors Motor pathways always begin with the cortex or nucleus. The most common one we need to know is the pyramidal or corticospinal pathway. Information in the pathway is traveling down from the brain which means that it is conscious control of skeletal muscle. It starts with pyramidal cell in precentral gyrus. The pyramidal cell axons create pyramids (inferior to pons in the medulla oblongata) The other one is the extrapyramidal pathway. Its information is subconscious control of skeletal muscle tissue and originates in the basal nuclei, and midbrain. ➢ Compare the location and funct...